TWI600245B - Power supplying circuit, power supplying system and power supplying method - Google Patents

Description

Power supply circuit, power supply system, and power supply method

The present invention relates to a power supply circuit, a power supply system, and a power supply method, and more particularly to a power supply circuit, a power supply system, and a power supply method of a portable computer device.

With the development of technology, portable computing devices equipped with rechargeable batteries, such as laptops, tablets, etc., have been widely used in daily life because they are convenient for users to carry. .

Portable computer devices typically receive external power through an AC-to-DC power adapter or a conventional power device to power the portable computer device and use an external power source to charge the rechargeable battery. The power supply system of the portable computer device generally uses a conventional power supply architecture or a narrow voltage direct current (NVDC) power supply architecture proposed by Intel to power the internal system components of the portable computer device.

Under the traditional power supply architecture, the supply voltage of the power adapter is directly supplied to a voltage regulator built into the portable computer device to be converted into a system load for driving the system in the portable computer device. Operating Voltage. In the narrow DC power supply architecture, the supply voltage of the power adapter is first converted to a charging voltage for charging the rechargeable battery via a built-in charging circuit, and then supplied to the voltage regulator circuit and the rechargeable battery. Can be charged due to the use of a narrow DC power supply architecture The lower battery voltage is directly converted to the operating voltage that can drive the system load. Therefore, the narrow DC power supply architecture has higher power conversion efficiency than the conventional power supply architecture when the system load is under light load. Today, most portable computer devices use a narrow DC power supply architecture to replace the traditional power supply architecture as a power supply architecture for portable computer devices.

However, when the power consumption of the internal system components of the portable computer device is greater, the supply voltage provided by the narrow DC power supply architecture needs to be converted by an additional boost circuit to drive the operation of each system component. Therefore, the voltage conversion efficiency of the narrow DC power supply architecture is inferior to the conventional power supply architecture under high load conditions, and also increases the burden on the rechargeable battery, thereby reducing the life of the rechargeable battery.

In view of this, an embodiment of the present invention provides a power supply circuit, a power supply system, and a power supply method. The power supply circuit, the power supply system, and the power supply method can be actively used according to the power consumption of the portable computer device. The power supply architecture or the narrow DC power supply architecture supplies power to improve the voltage conversion efficiency of the portable computer device system while also increasing the life of the rechargeable battery.

Embodiments of the present invention provide a power supply circuit adapted to receive an output of a power adapter to supply power to a battery unit and a system load. The power supply circuit includes a charging unit, a switching unit, and a voltage voltage stabilizing unit. The charging unit receives the first supply voltage output by the power adapter via a power input terminal, and the charging unit is configured to charge the battery unit. The switching unit is coupled to the power input end and an output end of the charging unit. The switching unit is configured to receive the first supply voltage and the second supply voltage output by the charging unit. The voltage voltage stabilizing unit is coupled to the switching unit. The voltage regulator unit is used to supply power to the system load. The switching unit provides a first supply voltage to the voltage stabilizing unit in a high load state, and the switching unit provides a second supply voltage to the voltage stabilizing unit in a low load state. The system load has a higher power consumption in a high load state than in a low load state.

Embodiments of the present invention provide a power supply system, and the power supply system is applicable. In a portable computer device, and the power supply system includes a power adapter and the above power supply circuit. The power adapter is coupled to an AC power source, and the power adapter is configured to rectify an AC voltage of the AC power source to generate a first supply voltage. The power supply circuit receives the output of the power adapter to supply power to the battery unit and system load. The power adapter and system load may be disposed on a motherboard.

In one embodiment of the present invention, the switching unit includes a power switching circuit and a control unit. The power switching circuit is coupled to the power input end, the output end of the charging unit, and the voltage voltage stabilizing unit. The power switching circuit is configured to establish a first power supply path between the power input terminal and the voltage voltage stabilizing unit or establish a second power supply path between the charging unit and the voltage voltage stabilizing unit. The control unit is coupled to the power switching circuit. The control unit is configured to detect power consumption of the system load, and correspondingly control the power switching circuit to turn on the first power supply path or turn on the second power supply path to provide the first supply voltage or the second supply voltage to the voltage voltage stabilization unit.

An embodiment of the present invention provides a power supply method suitable for driving the power supply circuit, and the power supply method includes the following steps. First, detect the operational status of the system load. Then, based on the detection result, the power source of the system load is determined. When the system load is in a high load state, the switching unit provides a first supply voltage to the voltage regulator unit to supply power to the system load. When the system load is in a low load state, the switching unit provides a second supply voltage to the voltage regulator unit to supply power to the system load. The system load has a higher power consumption under high load conditions than under low load conditions.

In summary, the embodiment of the present invention provides a power supply circuit, a power supply system, and a power supply method. The power supply circuit, the power supply system, and the power supply method can actively detect the portability when the portable computer device operates. The system power consumption of the computer device and determines the source of power for the operation of the system of the portable computer device. When the system power consumption of the portable computer device is large, the power supply circuit automatically supplies power to the system in a conventional power supply mode; when the system power consumption of the portable computer device is small, the power supply circuit is Will automatically switch The system is powered by a narrow DC power supply. Accordingly, the portable computer device can improve the voltage conversion efficiency of the portable computer device system by setting the power supply circuit provided by the present invention, and at the same time increase the life of the rechargeable battery, thereby improving the overall portable computer device. Operational efficiency.

The detailed description of the present invention and the accompanying drawings are to be understood by the claims The scope is subject to any restrictions.

1‧‧‧Power adapter

2‧‧‧ motherboard

21‧‧‧ battery unit

23‧‧‧Power supply circuit

231‧‧‧Charging unit

233‧‧‧Switch unit

2331‧‧‧Power switching circuit

VDD‧‧‧ operating voltage

MP1, MP2‧‧‧ PMOS transistor

R1, R2, R3, R4‧‧‧ resistance

Q1, Q2‧‧‧NPN transistor

2333‧‧‧Control unit

MCU‧‧‧Control Chip

235‧‧‧Voltage regulator unit

25‧‧‧System load

251‧‧‧Central Processing Unit

GND‧‧‧ ground terminal

LOAD_DET‧‧‧Detection signal

Vin‧‧‧First supply voltage

Vc‧‧‧second supply voltage

IL‧‧‧Output current

Ic‧‧‧Charging current

PT‧‧‧ power input

C10, C20, C30, C40, C50‧‧‧ curves

T1~T9‧‧‧ time

P_IH‧‧‧ power upper limit

P_IL‧‧‧ power lower limit

S100~S120‧‧‧Step procedure

S201~S211‧‧‧Step process

S301~S313‧‧‧Step procedure

1 is a functional block diagram of a power supply system according to a first embodiment of the present invention.

2 is a graph comparing power conversion efficiency of a narrow DC power supply architecture and a conventional power supply architecture according to a first embodiment of the present invention.

3 is a functional block diagram of a power supply system according to a first embodiment of the present invention.

4 is a circuit diagram of a switching unit according to a first embodiment of the present invention.

FIG. 5 is a schematic diagram of circuit operation of a switching unit according to a first embodiment of the present invention.

FIG. 6 is a schematic diagram of circuit operation of a switching unit according to a first embodiment of the present invention.

FIG. 7 is a schematic flow chart of a power supply method for a power supply system according to a second embodiment of the present invention.

FIG. 8 is a schematic flow chart of a power supply method for a power supply system according to a third embodiment of the present invention.

FIG. 9 is a schematic diagram showing the circuit operation waveform of the overcurrent protection circuit according to the third embodiment of the present invention.

FIG. 10 is a schematic flow chart of a power supply method for a power supply system according to a fourth embodiment of the present invention.

[First Embodiment]

Please refer to FIG. 1. FIG. 1 is a functional block diagram of a power supply system according to a first embodiment of the present invention. The power supply system can be applied to a portable computer device (not shown). In this embodiment, the portable computer device can be, for example, a notebook computer or a tablet computer, but the embodiment is limited thereto.

The power supply system includes a power adapter 1, a battery unit 21, a power supply circuit 23, and a system load 25, wherein the battery unit 21, the power supply circuit 23, and the system load 25 are respectively disposed on a motherboard 2. The motherboard 2 is disposed in a portable computer device. The power adapter 1 is coupled to the motherboard 2. The power supply circuit 23 is coupled between the power adapter 1 and the battery unit 21 and the system load 25.

The power adapter 1 is configured to rectify an AC voltage output from an AC power source (not shown) and generate a first supply voltage Vin to supply power to the electronic components on the motherboard 2, wherein the first supply voltage Vin is a DC voltage. The power adapter 1 can be electrically connected to the power input terminal PT of the portable computer device through a power cable (not shown) to output the first supply voltage Vin to the motherboard 2 through the power input terminal PT.

The battery unit 21 is built in a portable computer device. When the portable computer device is not connected to the power adapter 1, that is, when the power adapter 1 is not present, the battery unit 21 can be used to supply power to the system load 25 via the power supply circuit 23 to drive the operation of the system load 25.

The battery unit 21 may be a single rechargeable battery, such as a lithium ion battery (Lithium-Ion), a nickel cadmium battery (Ni-Cd), a nickel hydrogen battery (Ni-MH), or a rechargeable battery pack composed of a plurality of rechargeable batteries (rechargeable) The battery pack) is based on the type of the portable computer device and the actual architecture, and thus the embodiment is not limited.

In this embodiment, the battery unit 21 is integrally disposed on the motherboard 2, but in practice, the battery unit 21 can also be disposed in the motherboard of the portable computer device due to the internal internal structure of the portable computer device. Other housing spaces, such as a battery compartment for placing the battery unit 21 adjacent to the motherboard 2.

The power supply circuit 23 is configured to receive the output of the power adapter 1 via the power input terminal PT to supply power to the battery unit 21 and the system load 25. The power supply circuit 23 can actively configure the power source of the system load 25 according to the operating state of the system load 25.

In detail, the power supply circuit 23 actively selects the output of the power adapter 1 (ie, the first supply voltage Vin) or the input of the battery unit 21 (ie, the second supply voltage Vc) as the system load according to the power consumption of the system load 25. 25 power supply sources. That is, the power supply circuit 23 can actively select to supply the system load 25 in a narrow DC power supply mode or a conventional power supply mode according to the power consumption of the system load 25.

In this embodiment, the system load 25 can be, for example, all power consumption components built on the motherboard 2 of the portable computer device, including a central processing unit (CPU) (not shown in FIG. 1). The equivalent resistance of the system operation module (not shown) and peripheral devices (not shown). Incidentally, the actual architecture and implementation of the system load 25 may vary depending on the type and physical architecture of the portable computer device, and the architecture of the system load 25 is not a part of the present invention, and therefore is no longer Narration.

Further, the power supply circuit 23 includes a charging unit 231, a switching unit 233, and a voltage voltage stabilizing unit 235. The charging unit 231 is coupled between the power input terminal PT and the battery unit 21. The switching unit 233 is respectively coupled to the power input terminal PT and an output end of the charging unit 231. The voltage regulator unit 235 is coupled between the switching unit 233 and the system load 25.

The charging unit 231 is configured to receive the first supply voltage Vin output by the power adapter 1 via the power input terminal PT. The charging unit 231 generates a second supply voltage Vc according to the first supply voltage Vin output by the power adapter 1 and the power required to charge according to the battery unit 21 to charge the battery unit 21. In this embodiment, the voltage level of the second supply voltage Vc is smaller than the voltage level of the first supply voltage Vin.

In practice, the first supply voltage Vin generated by the power adapter 1 can be, for example, 19 volts (V), and the second supply voltage Vc output by the charging unit 231 may be, for example, 7.4 V volts (V).

In addition, the charging unit 231 can perform voltage conversion (eg, step-down) corresponding to the power required for charging the battery unit 21 to generate a second supply voltage Vc and a charging current Ic to charge the battery unit 21. The charging unit 231 can be implemented by a charging circuit, wherein the charging circuit includes a voltage conversion circuit. It is worth mentioning that the circuit architecture of the charging circuit, the manner in which the second supply voltage Vc and the charging current Ic are generated, and the charging method of the battery unit 21 are conventional techniques, and therefore will not be described again.

The switching unit 233 is configured to receive the first supply voltage Vin and the second supply voltage Vc output by the charging unit 231. The switching unit 233 is configured to detect the power consumption of the system load 25, and correspondingly switch the output of the first supply voltage Vin or the second supply voltage Vc to the voltage stabilization unit 235.

The voltage regulator unit 235 is used to supply power to the system load 25. Further, the voltage stabilizing unit 235 is configured to convert the output of the switching unit 233 into an operating voltage for driving the system load 25 according to the power requirement of the system load 25, for example, 5 volts (V), 1.7 volts, 3.3 volts, or 2.5 volts, etc., according to the operation of the drive system load 25. The voltage stabilizing unit 235 can be implemented by a voltage regulator or a voltage regulator circuit.

In this embodiment, the switching unit 233 selectively supplies the first supply voltage Vin output by the power adapter 1 or the second supply voltage Vc output by the charging unit 231 to the voltage voltage stabilization unit according to the power consumption of the system load 25. 235, to supply power to the system load 25.

In detail, the switching unit 233 provides a first supply voltage Vin to the voltage stabilizing unit 235 in a heavy load state, and the switching unit 233 provides a first in a light load state. The two supply voltages Vc are supplied to the voltage stabilizing unit 235, wherein the power consumption of the system load 25 in the high load state is greater than the power consumption in the low load state.

In short, the switching unit 233 selects to supply power to the system load 25 in a conventional power supply mode under high load conditions. In the low load state, the switching unit 233 selects to supply power to the system load 25 in a narrow DC power supply manner, thereby improving the power supply efficiency of the power supply system.

Specifically, in the present embodiment, the high load state indicates that the power consumption of the system load 25 is higher than a power upper limit value P_IH. The low load state indicates that the power consumption of the system load 25 is below a power lower limit value P_IL. In addition, when the power consumption of the system load 25 is between the power upper limit value P_IH and the power lower limit value P_IL, the switching unit 233 maintains the power supply source of the voltage voltage stabilizing unit 235. The power upper limit value P_IH is greater than the power lower limit value P_IL.

That is, in the case where the switching unit 233 supplies the first supply voltage Vin to the voltage stabilizing unit 235, the switching unit 233 continues to provide the first supply voltage Vin as long as the power consumption of the system load 25 is still higher than the power lower limit value P_IL. To voltage regulator unit 235. Similarly, in the case where the switching unit 233 supplies the second supply voltage Vc to the voltage stabilizing unit 235, the switching unit 233 continues to provide the second supply voltage Vc as long as the power consumption of the system load 25 is still lower than the power upper limit value P_IH. To voltage regulator unit 235.

In addition, when the switching unit 233 detects that the power consumption of the system load 25 gradually increases and enters the high load state, the switching unit 233 provides the first supply voltage Vin to the voltage voltage stabilizing unit 235; when the switching unit 233 detects the system load When the power consumption of 25 is gradually lowered and enters a low load state, the switching unit 233 supplies the second supply voltage Vc to the voltage stabilizing unit 235.

Accordingly, the switching unit 233 can be prevented from being misjudged when the system load 25 is unstable, and frequently switched between the narrow DC power supply mode and the conventional power supply mode to reduce the operational efficiency of the power supply system.

It is worth mentioning that the power upper limit value P_IH and the power lower limit value P_IL may be set according to the power consumption and power loss of the actual operation of the portable computer device. Please refer to FIG. 2, which illustrates a narrow straightness according to a first embodiment of the present invention. A graph comparing a power conversion efficiency of a power supply mode with a conventional power supply mode. 2 is generated based on the first supply voltage of the power adapter 1 output being 19 volts and the second supply voltage output by the charging single source 231 being 7.4 volts.

Curve C10 represents the voltage conversion efficiency that powers system load 25 using conventional powering methods. Curve C20 represents the voltage conversion efficiency of powering system load 25 using a narrow DC power supply. Curve C30 represents the power loss generated by powering system load 25 using conventional powering methods. Curve C40 represents the power loss generated by powering system load 25 using a narrow DC power supply.

It can be seen from the curve C10 and the curve C20 in FIG. 2 that when the output current IL of the voltage stabilizing unit 235 is about 23 amps (A), it is a voltage conversion efficiency separation point between the narrow DC power supply mode and the conventional power supply mode. When the output current IL of the voltage stabilizing unit 235 is less than 23 amps, the voltage conversion efficiency of the narrow DC power supply mode is greater than that of the conventional power supply mode. When the output current IL of the voltage stabilizing unit 235 is greater than 23 amps, the voltage conversion efficiency of the narrow DC power supply mode is smaller than that of the conventional power supply mode.

Therefore, the power upper limit value P_IH and the power lower limit value P_IL can be set according to the power consumption of the system load 25 when the output current IL is about 23 amps.

For example, taking the central processor in system load 25 as an example, the operating voltage of the central processing unit is typically 1.7 volts, that is, the power consumption of the central processing unit is 39 watts (W) at 23 amps. The power upper limit value P_IH can be further set to 42.5 watts depending on the output current IL of 25 amps, and the power lower limit value P_IL can be set to 35.7 watts depending on the output current IL of 21 amps.

When the power consumption of the system load 25 is greater than 42.5 watts (ie, the output current IL is greater than or equal to 25 amps), the switching unit 233 determines that the system load 25 is in a high load state and provides the first supply voltage Vin to the voltage regulator unit 235. . When the power consumption of the system load 25 is less than 35.7 watts (that is, the output current IL is less than or equal to 21 amps), the switching unit 233 determines that the system load 25 is in a low load state, and provides the second supply voltage Vc to the voltage regulator unit 235. .

In more detail, the switching unit 233 further includes a power supply switching circuit 2331 and a control unit 2333. The power switching circuit 2331 is coupled to the power input terminal PT, the output terminal of the charging unit 231, and the voltage voltage stabilizing unit 235. The power switching circuit 2331 is coupled to the control unit 2333.

The power switching circuit 2331 is configured to establish a first power supply path between the power input terminal PT and the voltage voltage stabilizing unit 235 or a second power supply path between the charging unit 231 and the voltage voltage stabilizing unit 235.

The control unit 2333 is configured to detect the power consumption of the system load 25 according to a detection signal LOAD_DET, and correspondingly control the power switching circuit 2331 to turn on the first power supply path or turn on the second power supply path to provide the first supply voltage Vin or the second supply. The voltage Vc is supplied to the voltage stabilizing unit 235.

Briefly, the control unit 2333 of the switching unit 233 drives the power switching circuit 2331 to turn on the first power supply path and provides the first supply voltage Vin to the voltage voltage stabilizing unit when the detection signal LOAD_DET indicates that the system load 25 is in a high load state. 235. The control unit 2333 drives the power switching circuit 2331 to turn on the second power supply path to provide the second supply voltage Vc to the voltage voltage stabilizing unit 235 when the detection signal LOAD_DET indicates that the system load 25 is in a low load state.

It is worth mentioning that the detection signal LOAD_DET is the power consumption corresponding to the system load 25. The detection signal LOAD_DET may be generated according to the output voltage VL of the voltage stabilization unit 235 and the output current IL. The control unit 2333 can actively determine the power consumption of the system load 25 according to the detection signal LOAD_DET at intervals (for example, every 240 milliseconds) to determine the power supply mode of the system load 25.

In one embodiment, the detection signal LOAD_DET may be generated by a current detecting component (not shown). Specifically, the current detecting component is coupled between the voltage stabilizing unit 235 and the control unit 2333. The current detecting component can be used to generate the detection signal LOAD_DET according to the output current IL output by the voltage regulator unit 235. The current detecting component can generate a corresponding voltage signal according to the output current IL outputted by the voltage stabilizing unit 235 as a detection signal LOAD_DET The control unit 2333 is configured by the control unit 2333 to determine the power consumption of the system load 25. In this embodiment, the current detecting component may be a resistive component, such as a resistor, but the embodiment is not limited.

For example, the control unit 2333 can detect the voltage signal generated by the current detecting component according to a preset sampling time (for example, every 60 milliseconds) for a period of time (for example, 240 milliseconds), and correspondingly record the output current IL. Then, the control unit 2333 calculates the average power consumption of the system load 25 based on the average value of the output current IL during the period of time to determine the power supply mode of the system load 25. During this period of time, the higher the sampling frequency, that is, the shorter the sampling interval, the more representative of the current power consumption of the system load 25. In the field of the invention, those skilled in the art should know how to set the sampling frequency according to the operation of the portable computer device to accurately detect and judge the power consumption of the system load 25, thereby selecting a better power supply mode and improving the portable computer. The voltage conversion efficiency of the system of the device.

In another embodiment, the control unit 2333 can be coupled to the system load 25 to receive the detection signal LOAD_DET of the output of the system load 25 to determine the power consumption of the system load 25. Please refer to FIG. 3. FIG. 3 is a functional block diagram of another power supply system according to the first embodiment of the present invention. The detection signal LOAD_DET may be provided by the central processor 251 in the system load 25. The central processing unit 251 can generate the detection signal LOAD_DET according to the current system operating state, and output it to the control unit 2333. For example, the detection signal LOAD_DET may be a status signal corresponding to a Global System State or a Processor Power State in an Advanced Configuration and Power Interface (ACPI) specification. The control unit 2333 can determine the power supply mode of the system load 25 by detecting the operating state of the portable computer device or the processor power state according to the detection signal LOAD_DET.

It should be noted that the embodiment does not limit the manner in which the detection signal LOAD_DET is generated, as long as the detection signal LOAD_DET can correspond to the power consumption of the system load 25. Those skilled in the art of the present invention should be able to infer from the above description how the detection signal LOAD_DET is generated and the manner of operation, and therefore will not be described again.

It is to be noted that the control unit 2333 may be a processor controlled by a microcontroller or an embedded controller, and the power consumption of the system load 25 is determined by a firmware programming manner. Corresponding to the system load 25 power source setting mode, but this embodiment is not limited. In an embodiment, the control unit 2333 can receive the detection signal LOAD_DET by using a general purpose input (GPI) of the microcontroller or the embedded controller, and utilizes a microcontroller or an embedded controller. A general purpose output (GPO) is used to control the operation of the driving power switching circuit 2331.

The specific implementation of the switching unit 233 and the circuit operation will be described in detail below. Please refer to FIG. 4 and refer to FIG. 1 at the same time. FIG. 4 is a schematic circuit diagram of a switching unit according to a first embodiment of the present invention.

In this embodiment, the power switching circuit 2331 includes NPN transistors Q1, Q2, PMOS transistors MP1, MP2, and resistors R1 R R4; the control unit 2333 includes a control chip MCU, and a general-purpose input pin of the control chip MCU is used. The detection signal LOAD_DET is received.

In one embodiment, the universal input pin of the control chip MCU may be coupled to a current detecting component (not shown) to determine the power consumption of the system load 25 according to the output of the voltage stabilizing unit 235. In another practice, the universal input pin of the control chip MCU can also be coupled to a central processing unit (not shown in FIG. 4) in the system load 25 to be based on the operating state of the central processing unit (eg, power consumption). ), the power consumption of the system load 25 is judged.

The first end of the resistor R1 is coupled to an operating voltage VDD. The second end of the resistor R1 is coupled to the first end of the resistor R2. The second end of the resistor R2 is coupled to a collector of the NPN transistor Q1. The emitter of the NPN transistor Q1 is coupled to the ground GND. The base of the NPN transistor Q1 is coupled to a general-purpose output pin (not shown) of the control chip MCU to be controlled by the control chip MCU. The first end of the resistor R3 is coupled to the base of the NPN transistor Q1, and the second end of the resistor R3 is coupled to the ground. Terminal GND. The resistor R3 is coupled to the common output pin of the control chip MCU and the ground GND. The resistor R3 is a pull-down resistor and is used to control the off-line operation of the wafer MCU or to float the general-purpose output pin of the control chip MCU, and pull down the general-purpose output pin of the control chip MCU to a zero voltage level. The resistor R3 can also be used to limit the amount of current flowing into the base of the NPN transistor Q1 to prevent the NPN transistor Q1 from being damaged from affecting the operation of the power switching circuit 2331.

A drain of the PMOS transistor MP1 is coupled to an output of the charging unit 231. The source of the PMOS transistor MP1 is coupled to the voltage regulator unit 235. The gate of the PMOS transistor MP1 is coupled to the output of the voltage dividing circuit formed by the resistors R1 and R2. Specifically, the gate of the PMOS transistor MP1 is coupled to the junction between the resistors R1 and R2, and is controlled by the voltage of the junction between the resistors R1 and R2, and the voltage of the junction between the resistors R1 and R2. The voltage across the resistor R1 is subtracted from the operating voltage VDD.

Incidentally, it is known to those skilled in the art that the voltage output to the gate of the PMOS transistor MP1 can be set by appropriately setting the operating voltage VDD and designing the resistance values of the resistors R1 and R2 to drive the PMOS. The operation of crystal MP1.

The first end of the resistor R4 is coupled to the operating voltage VDD to receive the operating voltage. The first end of the resistor R4 is coupled to the power input terminal PT. The drain of the PMOS transistor MP2 is coupled to the source of the PMOS transistor MP1 and the voltage regulator unit 235. The source of the PMOS transistor MP2 is coupled to the power input terminal PT. The source of the PMOS transistor MP2 is coupled to the operating voltage VDD. The gate of the PMOS transistor MP2 is coupled to the collector of the NPN transistor Q2. The NPN transistor Q2 is used to control the on and off operations of the PMOS transistor MP2. The collector of the NPN transistor Q2 is coupled to the second end of the resistor R4. The base of the NPN transistor Q2 is coupled to the collector of the NPN transistor Q1. In other words, the NPN transistor Q1 is used to drive the on or off operation of the NPN transistor Q2. The emitter of the NPN transistor Q2 is coupled to the ground GND.

Please refer to FIG. 5 and FIG. 6. FIG. 5 and FIG. 6 respectively illustrate a first embodiment of the present invention. A schematic diagram of the circuit operation of the provided switching unit.

When the control chip MCU determines that the system load 25 is in a high load state according to the detection signal LOAD_DET, the control chip MCU outputs a low voltage level control voltage to the base of the NPN transistor Q1 via its universal output pin to make the NPN transistor Q1 is turned off because the voltage across the base emitter is less than the turn-on voltage of the NPN transistor Q1 (eg, 0.6 to 07 volts). At this time, the gate voltage of the PMOS transistor MP1 is pulled up by the resistor R1 to a high voltage level, so that the PMOS transistor MP1 is turned off due to the source gate voltage being lower than the turn-on voltage of the PMOS transistor MP1. At the same time, the NPN transistor Q2 is turned on because the voltage across the base emitter is greater than the turn-on voltage of the NPN transistor Q1, and the gate voltage of the PMOS transistor MP2 is pulled down, and the PMOS transistor MP2 is turned on to form the first power supply path. . Accordingly, the first supply voltage Vin output from the power adapter 1 is supplied to the voltage regulator unit 235 via the PMOS transistor MP2.

When the control chip MCU determines that the system load 25 is in a low load state according to the detection signal LOAD_DET, the control chip MCU outputs a high voltage level control voltage to the base of the NPN transistor Q1 via its universal output pin to make the NPN electric The crystal Q1 is turned on because the voltage across the base emitter is greater than the turn-on voltage of the NPN transistor Q1.

At this time, the gate of the PMOS transistor MP1 is turned on by the NPN transistor Q1 being turned on and pulled down to the ground GND, so that the PMOS transistor MP1 is turned on because the voltage across the source gate is greater than the turn-on voltage of the PMOS transistor MP1. At the same time, the base of the NPN transistor Q2 will be turned off due to the NPN transistor Q1 being turned on and pulled down to the ground GND. The PMOS transistor MP2 is pulled up to the operating voltage VDD via the resistor R4, so that the PMOS transistor MP2 is turned off due to the cross-voltage between the source gates being smaller than the turn-on voltage of the PMOS transistor MP2, forming a second power supply path. . Accordingly, the second supply voltage Vc output by the charging unit 231 is supplied to the voltage stabilization unit 235 via the PMOS transistor MP1.

That is to say, when the system load 25 is in a high load state, the control chip MCU drives the power switching circuit 2331 to establish the self-power adapter 1 and the voltage voltage stabilization unit. The first power supply path between 235 and the second power supply path is cut off to supply the first supply voltage Vin to the voltage stabilizing unit 235. When the system load 25 is in the low load state, the control chip MCU drives the power switching circuit 2331 to establish a second power supply path between the self-charging unit 231 and the voltage voltage stabilizing unit 235 and cuts off the first power supply path to The supply voltage Vc is supplied to the voltage stabilizing unit 235.

It should be noted that FIG. 2 is only used to describe a graph comparing a power conversion efficiency between a narrow DC power supply mode and a conventional power supply mode, and is not intended to limit the present invention. FIG. 4 is only used to describe one circuit implementation of the switching unit 233, and is not intended to limit the present invention. Similarly, FIG. 5 and FIG. 6 are only schematic diagrams of circuit operations of the switching unit provided by the embodiment of the present invention, and are not intended to limit the present invention. In addition, the present embodiment does not limit the types, physical architectures, embodiments, and/or connection methods of the rechargeable battery 21, the charging unit 231, the switching unit 233, and the voltage voltage stabilization unit 235.

It should be noted that the coupling relationship between the components in the above embodiments includes direct or indirect electrical connection, as long as the required electrical signal transmission function can be achieved, and the present invention is not limited. The technical means in the above embodiments may be combined or used alone, and the components may be added, removed, adjusted or replaced according to their functions and design requirements, and the invention is not limited. After the description of the above embodiments, those skilled in the art should be able to infer the implementation and operation mode, and no further details are provided herein.

[Second embodiment]

According to the above embodiment, the present invention can be summarized as a power supply method suitable for driving the power supply circuit described in the above embodiment to manage the system load in a portable computer device (such as a notebook computer or a tablet computer). Power supply method. The power supply circuit may be disposed on a motherboard of the portable computer device. The portable computer device can receive the output of the power adapter 1 via the built-in power input to supply power to the built-in battery unit and system load.

Referring to FIG. 7 and FIG. 1 simultaneously, FIG. 7 is a schematic flowchart diagram of a power supply method for a power supply system according to a second embodiment of the present invention.

First, in step S100, the control unit 2333 of the switching unit 23 is based on one The signal LOAD_DET is detected to detect the operating state of the system load 25. The detection signal LOAD_DET corresponds to the power consumption of the system load 25.

In an embodiment, the detection signal LOAD_DET may be generated according to the output voltage VL of the voltage stabilization unit 235 and the output current IL. In another embodiment, the detection signal LOAD_DET may be generated by a central processor in the system load 25 according to its operating state. The specific generation manner of the detection signal LOAD_DET is detailed in the foregoing embodiment, and therefore will not be described again. The system load 25 can be all power consumption components of the aforementioned motherboard 2 built in the portable computer device, including a central processing unit (CPU) (not shown), a system operation module (not drawn Equivalent resistance, etc., and peripheral devices (not shown).

In step S110, when the control unit 2333 determines that the system load 25 is operating in the high load state according to the detection signal LOAD_DET, the control unit 2333 drives the power supply switching circuit 2331 to supply the first supply voltage Vin outputted by the power adapter 1 to the voltage regulator. Unit 235. In detail, the control unit 2333 drives the power switching circuit 2331 to establish a first power supply path between the power adapter 1 and the voltage voltage stabilizing unit 235 to supply the first supply voltage Vin outputted by the power adapter 1 to the voltage voltage stabilizing unit. 235 to supply power to the system load 25.

In step S120, when the control unit 2333 determines that the system load 25 is operating in the low load state according to the detection signal LOAD_DET, the control unit 2333 drives the power supply switching circuit 2331 to supply the second supply voltage Vc output by the charging unit 231 to the voltage stable state. Press unit 235. In detail, the control unit 2333 drives the power switching circuit 2331 to establish a second power supply path between the charging unit 231 and the voltage voltage stabilizing unit 235 to provide the second supply voltage Vc output by the charging unit 231 to the voltage voltage stabilizing unit. 235 to supply power to the system load 25.

The high load state indicates that the power consumption of the system load 25 is higher than a power upper limit value P_IH. The low load state indicates that the power consumption of the system load 25 is below a power lower limit value P_IL. The power upper limit value P_IH is greater than the power lower limit value P_IL. The power upper limit value P_IH and the power lower limit value P_IL may be as described above, the transmission ratio The voltage conversion efficiency (as shown in Figure 2) of the narrower DC power supply or the conventional power mode for the power consumption of different system loads is set. In addition, the power upper limit value P_IH and the power lower limit value P_IL may be implemented by first setting a memory (not shown) stored in the control unit 2333 in a firmware manner.

The power supply method of FIG. 7 may be performed by the control unit 2333 in the power supply circuit in the portable computer device. The control unit 2333 can process the chip, for example, by a microcontroller or an embedded controller, and implement the power supply method described in FIG. 7 through a firmware programming manner, but the embodiment is not limited thereto.

[Third embodiment]

According to the above embodiment, the present invention can further provide a power supply method suitable for driving the power supply circuit described in the above embodiment to manage a system in a portable computer device (such as a notebook computer or a tablet computer). The power supply mode of the load. Referring to FIG. 8 and FIG. 1 simultaneously, FIG. 8 is a schematic flowchart diagram of a power supply method for a power supply system according to a third embodiment of the present invention.

In this embodiment, the control unit 2333 of the switching unit 23 can preset and store the power upper limit value P_IH and the power lower limit value P_IL according to the power consumption and power loss of the portable computer device. The power upper limit value P_IH is greater than the power lower limit value P_IL.

First, in step S201, the control unit 2333 of the switching unit 23 detects the operating state of the system load 25 based on a detection signal LOAD_DET. The detection signal LOAD_DET corresponds to the power consumption of the system load 25.

Next, in step S203, the control unit 2333 may first determine the current power supply mode of the portable computer device. Specifically, the control unit 233 may first determine whether the power source of the system load 25 is the output of the power adapter 1. That is, the control unit 2333 determines whether the current power supply mode of the portable computer device is the conventional power supply mode. When the control unit 2333 determines that the power source of the system load 25 is the power adapter 1, step S205 is performed. On the other hand, when the control unit 233 determines that the power source of the system load 25 is the charging unit 231, step S209 is performed.

In detail, when the portable computer device is started, the system load 25 can be powered by the conventional power supply mode due to the power demand of the system load 25. That is, when the portable computer device is electrically connected to the power adapter 1, the control unit 2333 can drive the power switching circuit 2331 to establish the power adapter 1 and the voltage when the portable computer device is started. The first power supply path between the voltage stabilizing units 235 is to supply the first supply voltage Vin to the voltage stabilizing unit 235.

Next, in step S205, when the power source of the system load 25 is the power adapter 1, the control unit 2333 determines whether the power consumption of the system load 25 is less than a preset power lower limit value P_IL. If the power consumption of the system load 25 is lower than the preset power lower limit value P_IL, step S207 is performed. On the other hand, if the power consumption of the system load 25 is higher than the preset power lower limit value P_IL, return to step S201 to maintain the power supply source of the voltage stabilization unit 235 and continue to detect the power consumption of the system load 25.

In step S207, when the power consumption of the system load 25 is lower than the preset power lower limit value P_IL, that is, the system load 25 is in a low load state, the control unit 2333 drives the power switching circuit 2331 to cut off the first power supply path. And establishing a second power supply path between the output end of the charging unit 231 and the voltage stabilizing unit 235 to pass the second supply voltage Vc to the voltage stabilizing unit 235. Accordingly, the voltage conversion efficiency of the portable computer device in a low load state is improved.

In step S209, when the power source of the system load 25 is the charging unit 231, the control unit 2333 determines whether the power consumption of the system load 25 is higher than a preset power upper limit value P_IH. If the power consumption of the system load 25 is higher than the preset power upper limit value P_IH, step S211 is performed. On the other hand, if the power consumption of the system load 25 has not exceeded the preset power upper limit value P_IH, then return to step S201 to maintain the power supply source of the voltage voltage stabilizing unit 235 and continue to detect the power consumption of the system load 25.

In step S211, when the power consumption of the system load 25 is higher than the preset power upper limit value P_IH, that is, the system load 25 is in a high load state, the control unit 2333 drives the power supply switching circuit 2331 to cut off the second power supply path. And establish a power supply The first power supply path between the adapter 1 and the voltage stabilizing unit 235 is to pass the first supply voltage Vin to the voltage stabilizing unit 235. Accordingly, the voltage conversion efficiency of the portable computer device in a high load state is improved.

In short, in the power supply method of FIG. 8, when the power source of the system load 25 is the power adapter 1, and the power consumption of the system load 25 is higher than the power lower limit value P_IL, the control unit 2333 of the switching unit 233 will The continuous driving power switching circuit 2331 turns on the first power supply path to supply the first supply voltage Vin to the voltage stabilizing unit 235. Similarly, when the power source of the system load 25 is the charging unit 231, and the power consumption of the system load 25 does not exceed the power upper limit value P_IH, the control unit 2333 of the switching unit 233 continues to drive the power switching circuit 2331 to conduct. The second power supply path provides a second supply voltage Vc to the voltage regulator unit 235.

In other words, when the power consumption of the system load 25 is between the power upper limit value P_IH and the power lower limit value PIL, the control unit 2333 of the switching unit 233 maintains the power supply source of the voltage voltage stabilizing unit 235. Accordingly, the switching unit 233 can be prevented from being misjudged when the system load 25 is unstable, and frequently switched between the narrow DC power supply mode and the conventional power supply mode to reduce the operational efficiency of the power supply system. Therefore, the voltage conversion efficiency of the system of the portable computer device during operation can be provided, and the utility of the power supply circuit can be improved.

The operation of the power supply method described in FIG. 8 will be further described below. Referring to FIG. 9 and FIG. 1 simultaneously, FIG. 9 is a schematic diagram showing the operation waveforms of the power supply circuit according to the third embodiment of the present invention. Curve C50 illustrates the power consumption of the system load 25 of the portable computer device.

At time point T1, the power supply circuit of the portable computer device uses the first supply voltage Vin (for example, 19 volts) output by the power adapter 1 as a power source for the system load 25. At time point T1, the power supply circuit of the portable computer device supplies power to the system load 25 in a conventional power supply mode.

As shown in FIG. 9, when the control unit 2333 determines, according to the detection signal LOAD_DET, the power consumption of the system load 25 is between the power upper limit value P_IH and the power lower limit value. When P_IL (such as time point T1~T3), the control unit 2333 of the switching unit 23 drives the power switching circuit 2331 to maintain the power supply source of the voltage voltage stabilizing unit 235. That is, the control unit 2333 drives the power switching circuit 233 to continuously turn on the first power supply path, and supplies the first supply voltage Vin outputted by the power adapter 1 to the voltage voltage stabilizing unit 235.

When the control unit 2333 determines that the power consumption of the system load 25 is gradually reduced and is less than the power lower limit value P_IL according to the detection signal LOAD_DET, indicating that the system load 25 enters a low load state (such as time point T4~T5), the control unit 2333 will detect It is detected that the power consumption of the system load 25 is less than the power lower limit value P_IL (such as the time point T5), and the driving power supply switching circuit 2331 supplies the second supply voltage Vc (for example, 7.4 volts) output by the charging unit 231 to the voltage voltage stabilizing unit 235 to Power is supplied to the system load 25.

Between time points T6 and T7, although the control unit 2333 determines that the power consumption of the system load 25 is gradually increased according to the detection signal LOAD_DET, since the power consumption of the system load 25 has not exceeded the power upper limit value P_IH, the control unit 2333 The driving power supply switching circuit 2331 maintains the power supply source of the voltage stabilization unit 235. That is, the control unit 2333 drives the power switching circuit 233 to continuously turn on the second power supply path, and supplies the second supply voltage Vc outputted by the power adapter 1 to the voltage voltage stabilizing unit 235.

When the control unit 2333 determines that the power consumption of the system load 25 is higher than the power upper limit value P_IH according to the detection signal LOAD_DET, indicating that the system load 25 enters a high load state (such as the time point T8), the control unit 2333 drives the power switching circuit 2331. Switching, the first supply voltage Vin (for example, 19 volts) output from the power adapter 1 is supplied to the voltage stabilizing unit 235 to supply power to the system load 25.

Between time points T8, although the control unit 2333 determines that the power consumption of the system load 25 is gradually reduced according to the detection signal LOAD_DET, since the power consumption of the system load 25 has not dropped below the power lower limit value P_IL, the control unit 2333 The power supply switching circuit 2331 is driven to maintain the power supply source of the voltage regulator unit 235. That is, the control unit 2333 drives the power switching circuit 233 to be continuously turned on. The first power supply path supplies the first supply voltage Vin outputted by the power adapter 1 to the voltage stabilization unit 235.

In other words, when the control unit 2333 detects that the power consumption of the system load 25 is gradually decreasing and enters the low load state, the control unit 233 drives the power supply switching circuit 2331 to supply the second supply voltage Vc to the voltage voltage stabilizing unit 235. When the control unit 2333 detects that the power consumption of the system load 25 gradually increases and enters the high load state, the control unit 2333 provides the first supply voltage Vin to the voltage voltage stabilizing unit 235.

It is worth mentioning that the power upper limit value P_IH and the power lower limit value P_IL may be set according to the power consumption and power loss of the actual operation of the portable computer device. The power upper limit value P_IH and the power lower limit value P_IL may be implemented by previously setting a memory (not shown) stored in the control unit 2333 in a firmware manner.

[Fourth embodiment]

According to the above embodiment, the present invention can further provide a power supply method suitable for driving the power supply circuit described in the above embodiment to manage a system in a portable computer device (such as a notebook computer or a tablet computer). The power supply mode of the load. Referring to FIG. 10 and FIG. 1 simultaneously, FIG. 10 is a schematic flowchart diagram of a power supply method for a power supply system according to a fourth embodiment of the present invention.

In this embodiment, the control unit 2333 of the switching unit 233 can set and store the power upper limit value P_IH and the power lower limit value P_IL according to the power consumption and power loss of the portable computer device. The power upper limit value P_IH is greater than the power lower limit value P_IL.

In step S301, the control unit 2333 can actively detect the load current of the system load 25 according to the detection signal LOAD_DET every other preset time (for example, 60 milliseconds). In step S303, the control unit 2333 calculates and records the power consumption of the system load 25 based on the load current (ie, the output current IL of the voltage stabilizing unit 235) and the output voltage VL of the voltage stabilizing unit 235.

After the control unit 2333 and after a period of time (for example, 240 milliseconds), the system load 25 is calculated according to the recorded power consumption of the plurality of system loads 25 (for example, four). The average power consumption of the segment time is taken as the current power consumption of the system load 25. In another embodiment, the control unit 2333 may also be the time period, and finally the power consumption of the system load 25 is detected as the current power consumption of the system load 25.

Then, in step S305, the control unit 2333 determines whether the current power consumption of the system load 25 is greater than or equal to the previous power consumption. When the control unit 2333 determines that the current power consumption of the system load 25 is greater than or equal to the previous power consumption, the control unit 2333 performs step S307. On the contrary, when the control unit 2333 determines that the current power consumption of the system load 25 is less than the previous power consumption, the control unit 2333 performs step S311.

In step S307, the control unit 2333 further determines whether the current power consumption of the system load 25 is higher than a preset power upper limit value P_IH. When the control unit 2333 determines that the current power consumption of the system load 25 is higher than the preset power upper limit value P_IH, the control unit 2333 performs step S309. On the other hand, when the control unit 2333 determines that the current power consumption of the system load 25 is lower than the power upper limit value P_IH, the control unit 2333 drives the power supply switching circuit 2331 to maintain the power supply source of the voltage stabilization unit 235, and returns to step S301.

In step S309, the control unit 2333 determines that the system load 25 enters the high load state, and drives the power switching circuit 2331 to switch, and supplies the first supply voltage Vin (for example, 19 volts) output by the power adapter 1 to the voltage voltage stabilizing unit 235. Power is supplied to the system load 25. Control unit 2333 replaces the previous power consumption with the current power consumption.

In step S311, the control unit 2333 determines whether the current power consumption of the system load 25 is lower than a preset power lower limit value P_IL. When the control unit 2333 determines that the current power consumption of the system load 25 is lower than the preset power lower limit value P_IL, the control unit 2333 performs step S313. On the other hand, when the control unit 2333 determines that the current power consumption of the system load 25 is higher than the power lower limit value P_IL, the control unit 2333 drives the power supply switching circuit 2331 to maintain the power supply source of the voltage stabilization unit 235, and returns to step S301.

In step S313, the control unit 2333 determines that the system load 25 enters the low load state, and drives the power switching circuit 2331 to switch, and supplies the second supply voltage Vc (for example, 7.4 volts) output by the charging unit 231 to the voltage voltage stabilizing unit 235. Power is supplied to the system load 25. Control unit 2333 replaces the previous power consumption with the current power consumption.

The power supply method of FIG. 10 may be performed by the control unit 2333 in the power supply circuit in the portable computer device. The control unit 2333 can be a processing chip such as a microcontroller or an embedded controller, and the power supply method described in FIG. 10 is implemented by a firmware programming method, but the embodiment is not limited thereto.

It should be noted that FIG. 10 is only used to describe the power supply method for driving the power supply circuit provided in the portable computer device in the embodiment, and is not intended to limit the present invention.

[Possible effects of the examples]

In summary, the embodiment of the present invention provides a power supply circuit, a power supply system, and a power supply method. The power supply circuit, the power supply system, and the power supply method can actively detect the portability when the portable computer device operates. The system power consumption of the computer device and determines the source of power for the operation of the system of the portable computer device. When the system power consumption of the portable computer device is large, the power supply circuit automatically switches to power the system in a conventional power supply mode; when the system power consumption of the portable computer device is small, the power supply The circuit automatically switches to supply power to the system with a narrow DC power supply. Accordingly, the portable computer device can improve the voltage conversion efficiency of the portable computer device system by setting the power supply circuit provided by the present invention, and at the same time increase the life of the rechargeable battery, thereby improving the overall portable computer device. Operational efficiency.

In addition, the present invention can also be used as a basis for judging the traditional power supply mode or the narrow DC power supply mode by setting a power upper limit value and a power lower limit value, so as to avoid misjudgment caused when the portable computer device is unstable in system operation. Switching too frequently to the traditional power supply mode or narrow DC power supply mode to reduce the portable computer device The voltage conversion efficiency when the system is operating.

The above description is only an embodiment of the present invention, and is not intended to limit the scope of the invention.

1‧‧‧Power adapter

2‧‧‧ motherboard

21‧‧‧ battery unit

23‧‧‧Power supply circuit

231‧‧‧Charging unit

233‧‧‧Switch unit

2331‧‧‧Power switching circuit

2333‧‧‧Control unit

235‧‧‧Voltage regulator unit

25‧‧‧System load

LOAD_DET‧‧‧Detection signal

Vin‧‧‧First supply voltage

Vc‧‧‧second supply voltage

IL‧‧‧Output current

Ic‧‧‧Charging current

PT‧‧‧ power input

Claims (19)

A power supply circuit adapted to receive an output of a power adapter for supplying power to a battery unit and a system load, the power supply circuit comprising: a charging unit receiving a first supply output by the power adapter via a power input terminal The charging unit is configured to charge the battery unit; a switching unit is coupled to the power input end and an output end of the charging unit for receiving the first supply voltage and the output of the charging unit a second supply voltage; and a voltage voltage stabilizing unit coupled to the switching unit for supplying power to the system load; wherein the switching unit supplies the first supply voltage to the voltage voltage stabilizing unit under a high load condition The switching unit provides the second supply voltage to the voltage voltage stabilizing unit in a low load state, wherein the power consumption of the system load in the high load state is greater than the power consumption in the low load state; wherein the high The load state indicates that the power consumption of the system load is higher than a power upper limit value; the low load state indicates the power consumption of the system load Lower than a power lower limit value, wherein when the power consumption of the system load is between the power upper limit value and the power lower limit value, the switching unit maintains a power supply source of the voltage voltage stabilizing unit; wherein the power is The limit is greater than the lower power limit. The power supply circuit of claim 1, wherein when the power consumption of the system load gradually increases and enters the high load state, the switching unit provides the first supply voltage to the voltage voltage stabilizing unit; when the system is loaded The switching unit provides the second supply voltage to the voltage voltage stabilizing unit when the power consumption gradually decreases and enters the low load state. The power supply circuit of claim 1, wherein the switching unit comprises: a power switching circuit coupled to the power input terminal, the output terminal of the charging unit, and the voltage voltage stabilizing unit for establishing the power input a first power supply path between the terminal and the voltage voltage stabilizing unit or establishing the charging unit and the voltage a second power supply path between the voltage stabilizing units; and a control unit coupled to the power switching circuit for detecting power consumption of the system load, correspondingly controlling the power switching circuit to turn on the first power supply path or conducting The second power supply path provides the first supply voltage or the second supply voltage to the voltage regulator unit. The power supply circuit of claim 3, wherein the control unit is coupled to the voltage voltage stabilizing unit to determine a power consumption of the system load according to an output current output by the voltage voltage stabilizing unit. The power supply circuit of claim 3, wherein the control unit is coupled to the system load to determine a power consumption of the system load according to a detection signal of the output of the system load. The power supply circuit of claim 3, wherein the control unit actively detects the power consumption of the system load every predetermined time to correspondingly control the operation of the power switching circuit. The power supply circuit of claim 3, wherein the power switching circuit comprises: a first resistor, the first end of the first resistor is coupled to an operating voltage; and the second resistor is coupled to the first resistor The end is coupled to the second end of the first resistor; a first NPN transistor, the collector of the first NPN transistor is coupled to the second end of the second resistor, and the emitter of the first NPN transistor The first NPN transistor is coupled to the control unit; a third resistor is coupled between the base of the first NPN transistor and the ground; a PMOS transistor, a drain of the first PMOS transistor is coupled to the output end of the charging unit, and a gate of the first PMOS transistor is coupled to a second end of the first resistor, the first PMOS a source of the transistor is coupled to the voltage regulator unit; a second PMOS transistor, the drain of the second PMOS transistor is coupled to The source of the first PMOS transistor and the voltage stabilizing unit, the source of the second PMOS transistor is coupled to the power input end, and the source of the second PMOS transistor is coupled to the operating voltage, a gate of the second PMOS transistor is coupled to the second end of the fourth resistor; and a second NPN transistor, the collector of the second NPN transistor is coupled to the operating voltage via the fourth resistor, The collector of the second NPN transistor is coupled to the gate of the second PMOS transistor, the emitter of the second NPN transistor is coupled to the ground, and the base of the second NPN transistor is coupled The collector of the first NPN transistor. A power supply system includes: a power adapter coupled to an AC power source for rectifying an AC voltage of the AC power source to generate a first supply voltage; and a power supply circuit receiving the output of the power adapter Powering the battery unit to a system load, and the power supply circuit includes: a charging unit receiving the first supply voltage outputted by the power adapter via a power input terminal, and the charging unit is configured to perform the battery unit Charging; a switching unit coupled to the power input end and an output end of the charging unit for receiving the first supply voltage and a second supply voltage output by the charging unit; and a voltage voltage stabilizing unit, And being coupled to the switching unit for supplying power to the system load; wherein the switching unit provides the first supply voltage to the voltage voltage stabilizing unit under a high load state, and the switching unit provides the low voltage state a second supply voltage to the voltage voltage stabilizing unit, wherein a power consumption of the system load in the high load state is greater than the low load Power consumption in the state; wherein the high load condition indicates that the system load is higher than the upper limit value of power consumption of a power; represents the low load condition of the power system load is below a power consumption a lower limit value, wherein when the power consumption of the system load is between the power upper limit value and the power lower limit value, the switching unit maintains a power supply source of the voltage voltage stabilizing unit; wherein the power upper limit value is greater than The power lower limit. The power supply system of claim 8, wherein the switching unit provides the first supply voltage to the voltage voltage stabilizing unit when the power consumption of the system load gradually increases and enters a high load state; when the power of the system load The switching unit provides the second supply voltage to the voltage voltage stabilizing unit when the consumption is gradually lowered and enters a low load state. The power supply system of claim 8, wherein the switching unit comprises: a power switching circuit coupled to the power input terminal, the output end of the charging unit, and the voltage voltage stabilizing unit, wherein the power switching circuit is used Establishing a first power supply path between the power input terminal and the voltage voltage stabilizing unit or establishing a second power supply path between the charging unit and the voltage voltage stabilizing unit; a control unit coupled to the power switching circuit And detecting the power consumption of the system load, and correspondingly controlling the power switching circuit to turn on the first power supply path or turn on the second power supply path to provide the first supply voltage or the second supply voltage to the voltage Pressure unit. The power supply system of claim 10, wherein the control unit is coupled to the voltage voltage stabilizing unit to determine a power consumption of the system load according to an output current output by the voltage voltage stabilizing unit. The power supply system of claim 10, wherein the control unit is coupled to the system load to determine a power consumption of the system load based on a detection signal of the output of the system load. The power supply system of claim 10, wherein the control unit actively detects the power consumption of the system load every predetermined time to control the operation of the power switching circuit. The power supply system of claim 10, wherein the power switching circuit comprises: a first resistor, the first end of the first resistor is coupled to an operating voltage; a second resistor, the first end of the second resistor is coupled to the second end of the first resistor; a first NPN transistor, the collector of the first NPN transistor is coupled to the second resistor The second end of the first NPN transistor is coupled to a ground, the base of the first NPN transistor is controlled by the control unit, and a third resistor is coupled to the first NPN transistor. Between the base of the PMOS transistor and the first PMOS transistor, the drain of the first PMOS transistor is coupled to the output of the charging unit, and the gate of the first PMOS transistor is coupled to the gate a second end of the first resistor, the source of the first PMOS transistor is coupled to the voltage regulator unit; a second PMOS transistor, the drain of the second PMOS transistor is coupled to the first PMOS a source of the crystal and the voltage stabilizing unit, the source of the second PMOS transistor is coupled to the power input end, and the source of the second PMOS transistor is coupled to the operating voltage, the second PMOS a gate of the crystal is coupled to the second end of the fourth resistor; and a second NPN transistor, the collector of the second NPN transistor passes the fourth resistor The collector of the second NPN transistor is coupled to the gate of the second PMOS transistor, and the emitter of the second NPN transistor is coupled to the ground. The second NPN is coupled to the operating voltage. The base of the transistor is coupled to the collector of the first NPN transistor. The power supply system of claim 8, wherein the power supply circuit and the system load are disposed on a motherboard. A power supply method is applicable to the power supply circuit according to claim 1, wherein the power supply method comprises: detecting power consumption of a system load; determining a power supply source of the system load according to the detection result; and when the system load When the power consumption is higher than a power upper limit, the system is determined The system load is in a high load state, the switching unit provides the first supply voltage to the voltage voltage stabilizing unit to supply power to the system load; when the power consumption of the system load is between the power upper limit value and the power lower limit Between values, determining that the system load is in a low load state, the switching unit provides the second supply voltage to the voltage voltage stabilizing unit to supply power to the system load; and when the power consumption of the system load is between the power When the upper limit value is between the upper limit value and the power lower limit value, the switching unit maintains a power supply source of the voltage voltage stabilizing unit; wherein the power upper limit value is greater than the power lower limit value, and the system load is under the high load state The power consumption is greater than the power consumption under the low load state. The power supply method of claim 16, wherein the step of detecting power consumption of the system load comprises: detecting an output current of the voltage regulator unit output to the system load; and calculating according to the output current The power consumption of the system load. The power supply method of claim 16, further comprising: when the power consumption of the system load gradually increases and enters the high load state, the switching unit provides the first supply voltage to the voltage voltage stabilizing unit; and when The power consumption of the system load gradually decreases and when the low load state is entered, the switching unit provides the second supply voltage to the voltage voltage stabilizing unit. The power supply method of claim 16, further comprising: driving the switching unit to establish a first power supply path between the power input terminal and the voltage voltage stabilizing unit when the system load is in the high load state, Providing the first supply voltage to the voltage voltage stabilizing unit; and driving the switching unit to establish a second power supply path between the charging unit and the voltage voltage stabilizing unit when the system load is in a low load state, to provide The second supply voltage is to the voltage regulator unit.